Abstract:The drilling mud-filtrate invasion into reservoir makes resistivity log result deviate from the accurate resistivity. This deviation is related to invasion time. The model of time-lapse dual laterolog is used to study the dynamic responses of deep and shallow laterologs, and to discuss how time-lapse dual laterolog response varies with the changes of reservoir parameters. Compared with the usual method based on static profile model, time-lapse dual laterolog can offer plenty of correct data to favour our further understanding both of complexity in invasion process and of influence on log result. As a result, we have a new quantitative method for obtaining correct resistivity and hydrocarbon saturation of formation to nicely evaluate reservoir.